The present disclosure relates to an apparatus for controlling discharge of fuel vapor from a fuel tank. The fuel tank is the type which is used on motor vehicles. The present disclosure combines a control valve, liquid vapor separation and a flow management valve in a single housing. The apparatus includes a housing containing a first valve communicating with the fuel tank and a second valve which communicates with at least the first valve. A third valve communicates with the first valve and the second valve. A fourth valve communicates with the third valve and at least a vapor-recovery canister. The first valve controls discharge of pressurized fuel vapor from the tank during refueling. The second valve is a xe2x80x9crun-lossxe2x80x9d valve which operates to vent the fuel tank during vehicle operation. The third valve overlies portions of the first and second valves and blocks liquid fuel carryover from the tank to the vapor-recovery canister. The fourth valve provides flow management.
A variety of apparatus are available to control the escape of pressurized fuel vapor from a fuel tank during refueling. There is also a variety of apparatus which utilize a xe2x80x9crun-lossxe2x80x9d valve. These apparatus are part of a vapor recovery system used on many vehicles.
It is also desirable to provide a fuel tank which minimizes the space and volume requirements for mounting in a vehicle. Currently, many fuel tanks require a raised cavity therein for defining a xe2x80x9cvapor bubblexe2x80x9d. This vapor bubble area is used in the automatic shut off systems employed in modem fuel systems. At the point at which the valve shuts off, a vapor back pressure is created causing the inlet check valve to close and causing fuel to rise in the fill tube thereby activating an automatic shut off system employed on fuel dispensing systems. The vapor bubble area provides a space for expansion of the fuel during operation of the vehicle as well as a vapor recovery area within the tank.
Fuel tanks are often constructed of a multi-layer plastic material to prevent the escape of hydrocarbon emissions therethrough. Any interruption in the tank wall, such as a hole to mount a valve, requires sealing the hole. Each seal around a hole presents an opportunity for the escape of hydrocarbon vapors therethrough. With this in mind, it is desirable to minimize the number of interruptions or openings in the tank wall.
One of the problems encountered with prior art vapor-recovery apparatus is that they often employ multiple valves requiring multiple installations in the fuel tank. It would be desirable to minimize the number of installations in a fuel tank to minimize the number of interruptions in the fuel tank wall. It is desirable, however, to minimize the volume of the vapor bubble area in the tank. Due to the nature of the phenomenon, the vapor bubble portion of the tank is provided along the top area of the tank. The area external of the tank surrounding the bubble may be space which is not utilized in the vehicle design. As such it would be desirable to maximize the amount of usable space in the vehicle design. Alternatively, the vehicle must be altered in order to accommodate this vapor bubble in its design. As such, it would be desirable to minimize or eliminate the need to provide a vapor bubble area of a fuel tank.
Vapor recovery systems capture and recover escaping fuel vapor during the fueling process or event as well as during operation of the vehicle. The system to recover vapors escaping from the fuel tank through the system may employ a charcoal-filled canister which is designed to capture and store fuel vapors that are generated and displaced from the fuel tank during refueling and operation.
Such fuel recovery devices may be damaged if liquid fuel is introduced. As such, it is desirable to prevent the flow of liquid fuel from the tank to the vapor recovery canister. While a variety of apparatus have been designed to provide blocks and baffles to prevent liquid fuel from flowing from the tank to the vapor recovery canister, it would be desirable to provide an apparatus which prevents the flow of liquid fuel from the tank to the vapor recovery device as well as providing back up vapor and liquid control in the event of failure of the refueling valve. Allowing the liquid to be contained and provides a path for the liquid to reenter the tank.
Additionally, it would be desirable to provide a vapor recovery system which prevents the escape of fuel from the fuel tank during any angular condition of the vehicle, including, but not limited to, a roll over condition. A roll over condition occurs when the vehicle is substantially tilted or inverted. Under such conditions, the vapor recovery apparatus must be closed and sealed to prevent the escape of liquid fuel from the inverted tank and through the vapor recovery system.